Problem: Which of these numbers is composite? ${19,\ 59,\ 67,\ 69,\ 73}$
Solution: A composite number is a number that has more than two factors (including 1 and itself). 19, 59, 67, and 73 each have only two factors. The factors of 69 are 1, 3, 23, and 69. Thus, 69 is the composite number.